... to factor out fix for glibc 2.25 introduced in 7a5b301e3 (build: Use AC_HEADER_MAJOR to find device macros). Note: Once glibc 2.25 is old enough and this fix is not needed also AC_HEADER_MAJOR in configure.ac should be removed. Signed-off-by: Petr Vorel <pvorel@suse.cz> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>